The use of radiation (such as x-rays, protons, and so forth) to treat specific portions of the human body comprises a well-known area of endeavor. Generally speaking, such radiation serves to inhibit or destroy unwanted living material such as a tumor. Unfortunately, such radiation can be harmful to wanted portions of the patient's living material as well. Accordingly, treatment plans serve to control the radiation treatment process by attempting to maximize the therapeutic value of the radiation while minimizing collateral damage or risk.
It is known to modify a given treatment plan that extends over a given number of days or weeks (via a plurality of individual dosings) to accommodate certain dynamic physical changes that occur slowly over time. For example, the settings for a multi-leaf collimator may be altered to accommodate a change in the size of the treatment volume itself over time.
The applicant notes, however, that not all physical changes of relevance in a radiation-treatment setting occur slowly over time. In some cases, for example, real-time movements of the patient during the treatment process can materially impact the relative therapeutic value of the corresponding dosing. Depending upon the treatment plan, this can include both significant dynamic activity (as when the patient moves a limb) as well as relatively slight dynamic activity (as when the upper torso moves with the patient's breathing).
Other potentially relevant physical movement can derive from other objects in the radiation-treatment environment. In many cases, for example, the radiation source may move while administering radiation dosings. At the same time, or in lieu thereof, one or more patient support structures (such as all or portions of a couch) may move.
When such dynamic events occur during the treatment process the results can be undesirable. In some cases the movement can lead to physical conditions that vary so significantly from the assumptions of the treatment plan that attaining the desired therapeutic results becomes unlikely. In other cases the movement can lead to actual collisions between two or more structures in the radiation-treatment environment.
There are prior art approaches that seek to detect and accommodate in some fashion at least limited categories of such dynamic events. While perhaps successful for some limited purposes, the applicant has determined that there remains considerable room for improvement in these regards.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.